1. Field of the Invention
The present invention relates generally to conveyor systems and more particularly to a non-synchronous plural conveyor system for transporting articles between two work stations operating at varying production rates.
2. Description of the Prior Art
In product assembly operations, it is a common requirement that articles undergo sequential assembly steps at a number of separate work stations. The assembly steps, whether performed manually or automatically, require that the articles be transported from one work station to the next in an orderly fashion. In an ideally balanced system the output of a first work station is adequate to fully occupy the next without overloading.
Prior to the present invention three basic techniques have been used to move articles between work stations. The first and simplest involves the use of totes or trays which are filled with production articles at a first station, then moved to a second station where the articles are removed for the next and each subsequent operation. This technique is slow and cumbersome, strenuous to operators and not adapted for efficient use of production floor space. Core conveyors generally run continuously at a slow rate with assembly operators stationed along one or both sides. These are synchronous systems which remain in balance only so long as each individual operator functions at a rate no higher or lower than the design rate for the conveyor system. Of more recent vintage are power and free pallet systems which are complex and expensive and therefore of practical utility only for high volume automatic or near-automatic assembly operations.
None of the prior art conveyor systems is well suited to maximizing the production efficiency of assembly operations with work stations which operate at varying rates, as most do. Neither are the prior art systems particularly adaptable for efficient use in mixed; i.e. automated/manual assembly operations.